Netgear XCM8810 Chassis User Manual - Page 690

Areas, Internal router IR, Area border router ABR, Autonomous system border router ASBR

Page 690 highlights

NETGEAR 8800 User Manual Areas OSPFv3 allows parts of a network to be grouped together into areas. The topology within an area is hidden from the rest of the AS. Hiding this information enables a significant reduction in LSA traffic and reduces the computations needed to maintain the LSDB. Routing within the area is determined only by the topology of the area. The three types of routers defined by OSPFv3 are as follows: • Internal router (IR)-An internal router has all of its interfaces within the same area. • Area border router (ABR)-An ABR has interfaces in multiple areas. It is responsible for exchanging summary advertisements with other ABRs. • Autonomous system border router (ASBR)-An ASBR acts as a gateway between OSPFv3 and other routing protocols, or other autonomous systems. Backbone Area (Area 0.0.0.0) Any OSPFv3 network that contains more than one area is required to have an area configured as area 0.0.0.0, also called the backbone. All areas in an AS must be connected to the backbone. When designing networks, you should start with area 0.0.0.0 and then expand into other areas. Note: Area 0.0.0.0 exists by default and cannot be deleted or changed. The backbone allows summary information to be exchanged between ABRs. Every ABR hears the area summaries from all other ABRs. The ABR then forms a picture of the distance to all networks outside of its area by examining the collected advertisements and adding in the backbone distance to each advertising router. When a VLAN is configured to run OSPFv3, you must configure the area for the VLAN. If you want to configure the VLAN to be part of a different OSPFv3 area, use the following command: configure ospfv3 {domain } [vlan | tunnel ] area If this is the first instance of the OSPFv3 area being used, you must create the area first using the following command: create ospfv3 {domain } area Stub Areas OSPFv3 allows certain areas to be configured as stub areas. A stub area is connected to only one other area. The area that connects to a stub area can be the backbone area. External route information is not distributed into stub areas. Stub areas are used to reduce memory consumption and computational requirements on OSPFv3 routers. To configure an OSPFv3 area as a stub area, use the following command: 690 | Chapter 25. OSPFv3

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|
Chapter 25.
OSPFv3
NETGEAR 8800 User Manual
Areas
OSPFv3 allows parts of a network to be grouped together into
areas
. The topology within an
area is hidden from the rest of the AS. Hiding this information enables a significant reduction
in LSA traffic and reduces the computations needed to maintain the LSDB. Routing within the
area is determined only by the topology of the area.
The three types of routers defined by OSPFv3 are as follows:
Internal router (IR)
—An internal router has all of its interfaces within the same area.
Area border router (ABR)
—An ABR has interfaces in multiple areas. It is responsible for
exchanging summary advertisements with other ABRs.
Autonomous system border router (ASBR)
—An ASBR acts as a gateway between
OSPFv3 and other routing protocols, or other autonomous systems.
Backbone Area (Area 0.0.0.0)
Any OSPFv3 network that contains more than one area is required to have an area
configured as area 0.0.0.0, also called the
backbone
. All areas in an AS must be connected
to the backbone. When designing networks, you should start with area 0.0.0.0 and then
expand into other areas.
Note:
Area 0.0.0.0 exists by default and cannot be deleted or changed.
The backbone allows summary information to be exchanged between ABRs. Every ABR
hears the area summaries from all other ABRs. The ABR then forms a picture of the distance
to all networks outside of its area by examining the collected advertisements and adding in
the backbone distance to each advertising router.
When a VLAN is configured to run OSPFv3, you must configure the area for the VLAN. If you
want to configure the VLAN to be part of a different OSPFv3 area, use the following
command:
configure ospfv3 {domain <domainName>} [vlan <vlan-name> | tunnel
<tunnel-name>] area <area-identifier>
If this is the first instance of the OSPFv3 area being used, you must create the area first using
the following command:
create ospfv3 {domain <domainName>} area <area-identifier>
Stub Areas
OSPFv3 allows certain areas to be configured as
stub areas
. A stub area is connected to only
one other area. The area that connects to a stub area can be the backbone area. External
route information is not distributed into stub areas. Stub areas are used to reduce memory
consumption and computational requirements on OSPFv3 routers. To configure an OSPFv3
area as a stub area, use the following command: